The present invention relates generally to assemblies for swivel joints or loading arms, and more specifically, to an electrical conductivity assembly for establishing and maintaining electrical conductivity in a swivel joint and loading arm.
Loading or unloading arms are used to assist in the transfer of various materials, both wet or dry, from a supply source to a container, tanker car or truck in which materials are transported or shipped, or a vehicle, such as an airplane. Often, loading arms can be quite heavy and can be of considerable length. A swivel joint generally provides a mechanism making it easier to move the loading arm, and align it with the relatively small opening of a container. Since at times a loading arm needs to be handled by a single operator, it is preferable and desired to provide mechanisms or assemblies that will assist in rapid, easy and accurate placement of the end of the loading arm.
During the loading of various materials, static electricity may be generated. The voltage potential created causes the excited electrons to seek an area where the voltage potential is less. Surrounding metal, such as the loading arm, the container, or both can provide a low resistance to electrons and thus, may attract the electrons. Such static electricity should be dissipated preferably by routing or directing it to the ground, to the loading rack, or both.
Swivel joints, however, do not necessarily dissipate static electricity. In some instances, they do not have a tight or constant metal-to-metal contact because they are configured to permit relative rotational movement of the components to position the loading arm, as desired. Grease, oil and other lubricants often fill the cavity between the adjacent components further inhibiting metal-to metal contact. Effective breaks in the metal-to-metal contact for periods of time, even brief period of time, such as when there is not a sufficient load on the loading arm or at various relative positions, may electrically isolate adjacent components, which is not entirely suitable as a ground system to assist in dissipating static electricity.
In some cases, the material being routed through a loading arm may offer a path of less electrical resistance that the electrical conductivity offered by the adjacent metal components of the swivel joint (e.g., the tail and body sections). Such a situation could result in an undesirable consequence, and/or serious injury, especially if the material being routed through the loading arm is violative, such as gasoline, chemicals, and the like.
One example of a prior electrical conductivity system used with swivel arms is shown in U.S. Pat. No. 290,844 (Bowman). The tail and body sections are maintained in sufficient electrical communication with an external device that is attached to the exterior of the loading arm""s adjacent metal components. This design offers a path of low resistance and allows electrical current to be routed to adjacent metal pieces on a separate wire. Such assemblies, such as the one illustrated in Bowman, have a number of shortcomings. For example, the exterior wire can limit rotational movement of the swivel joint. Also, the external wire may become tangled and can limit rotational movement based on its length. Furthermore, the design illustrated in Bowman is prone to become detached, as it is not isolated from climate or environmental considerations.
As can be appreciated, currently available swivel joints for a loading arm have a number of shortcomings that contribute to the complexity of the assemblies, and overall reliability and usefulness of the loading arm equipment in general. There exists a continuing need in the industry for a swivel joint that can be adjusted accurately and quickly while providing sufficient electrical conductivity between the metal components of the device while the loading arm is in any position and under any load condition.
It is an object of the present invention to provide an assembly that addresses and overcomes the above-mentioned problems and shortcomings in the loading arm and swivel joint industry.
It is yet another object of the present invention to provide an assembly that effectively and reliability maintains electrical communication or conductivity between rotatable metal components.
Still another object of the present invention is to provide an assembly that includes an integral electrical conductivity assembly.
A further object of the present invention is to provide an assembly that can meet a wide range of operating requirements.
Another object of the present invention is to provide an assembly that allows a more full range of rotational adjustment.
Additional objects, advantages, and other features of the invention will be set forth and will become apparent to those skilled in the art upon examination of the following, or may be learned with practice of the invention.
To achieve the foregoing and other objects, and in accordance with the purposes herein, the present invention comprises a swivel joint assembly, preferably having a full range of rotational movement, can include a body pipe and a cooperating tail pipe that fit together for form a fluid passage. A sealing element and rotational assist mechanism can be interposed between the interior surface of the body pipe and the exterior surface of the cooperating tail pipe. An electrical connector, such as a spring plunger, can extend through the bore hole in the body pipe and has a first portion in effective electrical communication with the body pipe and a second portion in effective electrical communication with the tail pipe.
In some embodiments, the electrical connector may be threaded, and/or selectively removable from the bore hole.
In a preferred embodiment, the exterior surface of the tail pipe may include a groove and/or the electrical connector may have a ball shaped end that is receivable within the groove.